Hopes of a reprieve from soaring oil prices mounted yesterday as Saudi Arabia claimed fellow members of the Opec oil cartel were working on bringing down the cost of crude.

Oil continued its week-long surge yesterday, sending Brent crude above $120 a barrel and fuelling fresh concerns about the cost of petrol.

"We are seeing a prolonged period of high oil prices," the Saudi oil minister Ali al-Naimi said. "We are not happy about it. Saudi Arabia is determined to see a lower price and is working towards that goal."

Higher output from the Saudis helped to break a two-year cycle of tightening supply conditions in the oil market, according to the International Energy Agency's latest report. But Brent crude has still risen about 13 per cent this year, with oil trading above $100 for all but a handful of days, stirring fears the surging cost will threaten the global economy's recovery.

Mr Naimi's comments came as the market prepared for a crunch meeting of major powers with Iran – Opec's second-largest crude producer – this weekend to discuss export sanctions and its nuclear programme.

Iran's President Mahmoud Ahmadinejad said his country "will not retreat an iota" from its nuclear plans.

Concern about the tensions in Iran have supported oil prices for months, with some analysts estimating they have added $10-$15 a barrel. Other factors include concerns about a supply shortage due to production problems.

Mr Naimi tried to alleviate those fears, saying there were no supply problems in the global oil market and that Saudi Arabia was ready to use its spare production capacity if necessary.